Pesticidal compositions

ABSTRACT

A composition for the controlled release of an essential oil having pesticidal or fungicidal activity comprises a carrier material for said essential oil and a component that controls the release of said essential oil from the carrier material.

This invention is concerned with compositions for controlling pests,microbes and fungi that affect the cultivation of ornamental andagricultural plants, crops and trees, and to methods of forming same.

There is considerable consumer interest in the provision of pesticidesand fungicides that are capable of effectively controlling pests anddiseases that afflict, for example ornamental and agricultural plants,crops and trees, and affect the storage of crops, fruits and seeds, butwhich are not regarded as harmful to mammals or the environment. Oneapproach to environmentally friendly products is to use essential oilswhich are known to have pesticidal and/or fungicidal properties (see forexample Gudrip Singh et al “Essential Oils: A potent source of naturalpesticides”; Journal of Scientific & Industrial Research, 52, 676-683(October 1993)).

Essential oils have been mixed with conventional inorganic or organiccarrier materials of synthetic or natural origin such as talc,diamataceous earth, calcium phosphates, calcium and magnesiumcarbonates, flours, saw dust, corn cobs and tobacco stalks, and used inpesticidal or herbicidal applications in household or agricultural use(see, for example, International Publications WO 00/51436 or WO01/10214). However, essential oils are volatile and display a propensityto evaporate rapidly and uncontrollably when simply absorbed on tocarriers. Furthermore, for outdoor use, rain or irrigation water mayeasily wash the oils from conventional carriers.

Volatile oils used in flavour and fragrance applications have beenencapsulated in polymer-coated particles for use in the consumerproduct, cosmetic, and food industries. However, having regard to theparticular end uses of these products, such particles are adaptedessentially to prevent release of the volatile oils until such time asthey are exposed to exogenous stimuli such as dissolving media, e.g.water or aqueous media, or mechanical action generated by, for examplechewing or rubbing of a composition onto skin, whereupon the particlesprovide the volatile oils to the user rapidly in a rushing or burstingmanner.

There remains a need to provide compositions of volatile activematerials, and in particular essential oils, for use in pesticidal orfungicidal applications that can release said active materials in acontrolled manner over a prolonged period of time, in particular underconditions of elevated temperature and/or humidity that may beencountered in, for example agricultural use. Therefore, the inventionprovides in a first aspect a controlled release composition comprisingan essential oil having pesticidal and/or fungicidal properties, asupporting material therefor and means for controlling the release ofthe essential oil from the supporting material.

Controlled release compositions (hereinafter “compositions”) of thepresent invention are useful for the release of essential oils or othervolatile agents having pesticidal and/or fungicidal properties in acontrolled manner and over prolonged periods of time. The essential oilsare therefore released into the environment in a sensitive manner, thatis, in controlled amounts such that the concentration in the environmentis sufficiently high to treat the pest or disease state, but which doesnot reach levels that are excessive for the purpose intended. Further,the compositions may be made of relatively cheap raw materials and areof relatively simple construction.

Essential oils or other volatile active agents as hereinabove describedare preferably substances having a vapour pressure greater than 1.10⁻⁴mm Hg at 25° C., more preferably 1.10⁻³ mm Hg at 25 degrees centigrade.More preferably, the essential oils are materials that are non-toxic tomammals and the environment. By “essential oils” is meant volatilechemicals that may be the extracted essential oils from plants, or theactive components of those oils, which have pesticidal and/or fungicidalactivity. Representative examples include essential oils such asrosemary, thyme, lavender, eugenol, geranium, tea tree, clove, lemongrass, sweet flag root, woodruf, pyretrum flower, peppermint, garlic,cedar, mint, eucalyptus, jasmin, lavender, fennel, ginger, grapefruit,lemon, mandarin, orange, pine needle , tangerine, wintergreen, mustardseed, capsicum, pepper or their active components such as anethole,carvacrol, citonellal, citral, eugenol, linalool, 2,6-nonadienals,iso-eugenol, D-pulegone, carvone, alpha terpineol, cinnamic alcohol,cinnamic aldehyde, thymol, eucalyptol, farnesol, menthol, 1-carvone,limonene, pyrethrins, methyl salicylate, terpineol, beta asarone, methylanthranilate, methyl salycylate, allyl isothiocynate, coumarine,propenyl propyl disulphide, camphor, nerolidol, geraniol, and mixturesthereof. The use of particular oils or components, or mixtures of samewill depend upon the specific pest/fungus to be controlled and a personskilled in the art will have no problem in making appropriateselections.

In a first preferred embodiment of a composition according to thepresent invention, the supporting material may be a material, e.g. apowder material, that is capable of absorbing the essential oil to anextent that the resultant mixture is in the form of a free-flowingpowder, and it may be selected from materials that include for example,clays; silicas; celites; zeolites; metal salts, including for example,phosphates; cellulose, such as methyl cellulose; starches; carbonates,such as sodium bicarbonate; borates, such as sodium borate; sulfatessuch as sodium sulfate; water soluble polymers; borax; and mixturesthereof.

The means for controlling the release of the essential oil from thesupporting material (“controlling means”) as used in this firstpreferred embodiment may be a high molecular weight, low melting wax orsolid that may be mixed readily with the support material. Examples ofsuitable controlling means for use in the present invention includepolyethylene glycol, glycerol, mineral oil, and mixture thereof. Themolecular weight of said controlling means in the present inventionmight vary between about 400 Daltons to about 20,000 Daltons, preferablybetween about 2,000 Daltons to 10,000 Daltons. Other controlling meanshaving a similar viscosity and melting point to polyethylene glycol arealso contemplated as useful in said first preferred embodiment.

In a preferred first embodiment, the composition comprises from 5 to 50%by weight of active agent; 0.2 to 10% by weight of controlling means;and 95 to 50% by weight of support material. Insofar as clays areemployed as components of the support material, it is preferred thatthese clays be not present in amounts exceeding 50% by weight, morepreferably not exceeding 15% by weight based on the total amount ofsupport material. The amounts of each component may vary within theselimits, provided that the resultant composition is in the form of afree-flowing powder, that is, a powder that is resistant to clumping orcaking, and that may be easily poured from a container leavingessentially no residues in the container. Compositions may be consideredto be free-flowing if 500 grams of the composition are placed into a onelitre glass beaker and left overnight, and that all, or substantiallyall, of the composition, when the beaker is slowly tilted, is dispensedwithout having to mechanically dislodge it from the beaker. By“substantially all” is meant greater than 90% by weight is dispensed,more particularly greater than 95% is dispensed.

Preferably, the ratio of essential oil to support material is about 1:20to about 1:1, more preferably about 1:5. The ratio of essential oil tocontrolling means is about 50:1 to about 2:1, more preferably about20:1.

Said first preferred embodiment may be manufactured according to aprocess comprising the steps of mixing the active agent with thecontrolling means to form a premix, and mixing together the premix withthe support material to form a free-flowing powder. Further details of asuitable process are set forth in the Example 1 below.

In a second preferred embodiment of a composition according to thepresent invention the composition is in the form of a capsule whereinthe supporting material is provided as a core material and the means forcontrolling the release of the active agent from the supporting material(“controlling means”) is provided as a coating material coating saidcore material.

The coating material is preferably a water-insoluble polymeric materialthat may be useful in controlling the release of essential oil from thecore material. Preferably the coating is formed from a suitable protein,carbohydrate or a synthetic polymer. More preferably a protein coatingis employed in the present invention. Examples of suitable proteinsinclude gelatin, albumin, casein or lacto-glogulin, and in particulargelatin. Any type of gelatin that may be employed in the manufacture ofcapsules for use in food, consumer product and medicinal fields may beemployed in the present invention. However, a particularly preferredgelatin is 250 Bloom Type A gelatin. The coating material mayadditionally comprise other adjuvants useful in the manufacture ofcapsules, such as any of the carbohydrates, or synthetic polymers, e.g.polyvinylpyrollidone or methylcellulose commonly known and used incoating materials.

The coating may be crosslinked or not crosslinked. When employed,crosslinking agents include any of those crosslinking agents known andused in making capsules and gelatin-containing capsules in particular.They include formaldehyde or glutaraldehyde. Other known crosslinkingagents include tannic acid, alum, or naturally occurring enzymes such astransglutaminase.

The core material may comprise an oil that may be selected from a widerange of oils having different chemical natures. The oils may beselected from mineral oils (petroleum or petroleum-derived), vegetableoils (e.g. from seeds and nuts) and animal oils, e.g. fats and fishoils. Preferably, the oil is selected from mineral, vegetable or benzylalcohol. In a more preferred embodiment the oil is a short-chaintriglyceride of fractionated coconut oil, available under the tradenames Miglyol (Huls Corporation Piscataway N.J.), or Captex (AbitecCorp. Janesville Wis.).

The composition according to the second preferred embodiment may be inthe form of a free-flowing powder within the meaning given to this termabove, and may consist of particles having a mean diameter greater than0.01 mm and less than 2 mm.

The composition of the second preferred embodiment may comprise 5 to 50%by weight of active agent, more particularly about 20% by weight.

The composition of the second preferred embodiment may be prepared bypre-forming a capsule comprising a coating surrounding an oil-containingcore, and absorbing the active agent across the coating of the capsuleinto the core. This process may proceed according to a coacervationprocess as described in U.S. Pat. Nos. 6,106,875 and 6,045,835.Preferred capsules used in a process according to this methodology arecommercially available under the Trade mark “Flavourburst”, GivaudanFlavours Corporation, Cincinnati, Ohio, USA.

Any of the compositions hereinabove defined may additionally compriseone or more optional auxiliary agents. As auxiliary agents there arementioned any agent that imparts a benefit to said compositions. Suchauxiliary agents may include, for example, flow aids, which ameliorateor eliminate caking or stickiness of the composition, e.g. hydrophobicsilica and aluminosilicates; pigments; dyes; surfactants; emulsifiers;binders, e.g. starches, gums, glues, and mixtures thereof; enzymeinhibitors; antioxidants; pH modifier; fillers, e.g. cellulose, sand,soil, ground rock, fly ash, and mixtures thereof; and mixtures of any ofthe above.

Auxiliary ingredients aforementioned may be used in compositions inamounts of up to 50% by weight of the composition.

Compositions according to the present invention may be used alone inpesticidal and/or fungicidal applications, or they may be mixed withadditional carrier material which may facilitate their application tothe plant, seed, soil or other object to be treated, or improve storage,transport and/or handling of the composition. In general, any of thematerials customarily employed in formulating pesticides or fungicides,are suitable. Suitable carrier materials include known inorganic ororganic diluents or extenders of synthetic or natural origin, and may beselected from talc, attapulgite clay, kieselguhr, pyrophyllite, chalk,diatomaceous earth, vermiculite, calcium phosphates, calcium andmagnesium carbonates, sulfur, flours, and other organic and inorganicsolids which act as carriers for the pesticide and/or fungicides.Particularly preferred are particles of organic materials which arepreferably biodegradable, e.g. ground corn cob, corn stalks, cherrypits, wood shavings, hulls of cereal grains, saw dust, coconut shells,tobacco stalks and ashes of organic matter and the like.

The composition and carrier material may be mixed such that the carriermaterial is present at 30% (wt) to 98% (wt) based on the total weight ofthe mixture.

The amount of composition used in pesticidal or fungicidal use willdepend upon the particular condition to be treated, the nature of theenvironment (e.g. for use indoors or outdoors, e.g. in an agriculturalfield). Typically however, for agricultural use, it is contemplated thata kilogram quantity of composition containing 20% of essential oil maybe mixed with a carrier material as aforementioned to treat an area ofhalf an acre.

The composition according to the invention may be delivered in amultitude of ways. The composition may be contained in a sachet thatallows egress of the essential oil, such that when the composition isplaced in an environment, it will release the essential oil to theenvironment in a slow and controlled manner. Alternatively, thecomposition may be provided as a powder to be strewn over an area to betreated. Over relatively small areas compositions may be scattered byhand, although for large-scale agricultural operations, conventionaltechniques known in the art may be employed to distribute compositionand carrier over large areas, for example spraying techniques.

Compositions according to the present invention deliver essential oil toan environment to be treated in a controlled and prolonged manner, thatis, essential oil may be dispensed in a substantially uniform manner forperiods 1 week or more depending upon the environmental conditions andthe degree of infestation.

The following examples are provided to further illustrate thecompositions and processes of the present invention. These examples areillustrative only and are not intended to limit the scope of theinvention in any way.

EXAMPLE 1

A composition is formed by combining the following components:Ingredient Type Ingredient Name %(w/w) Active agent Garlic Oil 20Controlling Polyethylene Glycol 4000 1 means Clay Bentonite 10 ZeoliteVALFOR ™ 100 69

The garlic oil is mixed into the controlling means. The support material(i.e. clay and zeolite) are blended in a mixing vessel. Half of theliquid portion (i.e. garlic oil/controlling means mixture) is then addedto the mixing vessel with stirring. The components are mixed until theliquid portion is well incorporated into the supporting material. Then,the rest of the liquid portion is mixed until the composition is in theform of a free flowing powder (composition 1).

10 grams of the composition 1 is added to 200 grams of corncob(OLOBLAST™ 14-40) and mixed well. The mixture is spread evenly over aplastic spray. A control is made by adding 2 grams of the garlic oil to200 grams of corncob (OLOBLAST 14-40) and mixing well. The composition 1and the control are split into two sets each and the sets are spreadevenly on to plastic trays. The trays are placed in an outsideenvironment but protected against rain. One set of each was left dry andthe second set was sprayed with 20 grams of water daily and assessedafter it had been left to dry for 4 hours. The sets were tested by 6trained panellists for emission of the garlic oil over a period of 8days. The results shown in the Tables below demonstrate that release ofthe garlic oil is perceptible from composition 1 in a substantiallyconstant manner over a period of 8 days, whereas with the controlsample, there is an initial strong emission of the volatile oil whichtapers off quickly such that after only after 2 days, the intensity ofthe odour of the garlic oil is very low. Sensory Evaluation Dry No wateradded Results Sample Day 1 Day 2 Day 3 Day 4 Day 5 Day 8 Control 3.5 2.71.5 1.5 1.5 1.5 Composition 1 5.0 5.0 5.0 5.0 4.5 4.0 Water addedSensory Evaluation Wetted Results Sample Day 1 Day 2 Day 3 Day 4 Day 5Day 8 Control 2.5 2.5 1.5 1.5 1.5 1.4 Composition 1 4 4.5 4.0 4.0 4.03.5

EXAMPLE 2

The above experiment is repeated replacing the garlic oil with geranioland using two carriers corncob (OLOBLAST 14-40) and Bentonite clay. Theresults below show that the composition 1 is providing a constant odouremission over 8 days. And the control odour emission drops off to a weakintensity. Sensory Evaluation Dry No added water Results Sample Day 1Day 2 Day 3 Day 4 Day 5 Day 8 Control 3.0 2.4 1.5 1.4 1.2 1.2 (corn cob)Composition 1 4.0 4.3 4.0 4.0 4.0 3.6 (Corn cob) Control (Clay) 3.0 2.31.4 1.4 1.0 1.0 Composition 4.5 4.5 4.5 4.5 4.0 3.3 1 (Clay)

EXAMPLE 3

Dry blank capsules are prepared according to the methodology set forthin the International Publication WO 99/17871. 70 parts blank capsules isplaced in a 5-litre glass beaker and to the capsules are added garlicoil (20 parts), demineralised water (4 parts) and ethyl alcohol (6parts). The resultant mixture is stirred on a magnetic stirrer for 2minutes. Thereafter, the container is sealed and the mixture allowed toincubate for 24 hours to provide garlic oil-filled capsules (composition2).

10 grams of the composition 2 is added to 200 grams of corncob (OLOBLAST14-40) and mixed well. The mixture is separated into two sets and eachset spread evenly over plastic trays. The composition 2 is thereaftercompared as in Example 1 against sets of control sample. No WaterSensory Evaluation Dry Added Results Sample Day 1 Day 2 Day 3 Day 4 Day5 Day 8 Control 3.5 2.7 1.5 1.5 1.5 1.5 Composition 2 2.5 3.1 3.2 3.03.0 3.0 Water Sprayed on Sensory Evaluation Wetted Results Sample Day 1Day 2 Day 3 Day 4 Day 5 Day 8 Control 2.5 2.5 1.5 1.5 1.5 1.5Composition 2 3.0 3.1 3.3 3.2 3.0 2.6

The results shown in the Table above demonstrate that release of garlicoil is perceptible from composition 2 in a constant manner over a periodof 8 days, whereas with the control sample, there is an initial strongemission of garlic oil which tapers off quickly such that after only 2days, the odour of garlic is weak.

EXAMPLE 4

The procedure as outlined in Example 3 is repeated with geraniolreplacing garlic oil and using two carriers, viz. corncob (OLOBLAST14-40) and Bentonite clay. The results are shown in the Table below.Water Sprayed on Sensory Evaluation Wetted Results Sample Day 1 Day 2Day 3 Day 4 Day 5 Day 8 Control 2.5 2 1.5 1.4 1.0 1.0 (Corn Cob)Composition 3.0 3.0 3.2 3.0 3.0 2.6 2 (Corn Cob) Control (Clay) 2.0 2.01.4 1.0 1.0 1.0 Composition 3 3.5 3 3 3 2.6 2 (Clay)

The composition 2 maintains the intensity of the geraniol odour for atleast 8 days, whereas the odour of the control system drops to very weakafter 2 days.

1. A controlled release composition comprising an essential oil havingpesticidal and/or fungicidal properties, a supporting material thereforand means for controlling the release of the active agent from thesupporting material.
 2. A composition according to claim 1 wherein thesupporting material is a material capable of absorbing the essential oilto the extent that the resultant mixture is in the form of afree-flowing powder; and the means controlling the release of theessential oil from the supporting material is a high molecular weight,low melting point wax or solid that may be mixed readily with thesupport material.
 3. A composition according to claim 2 wherein thesupport material is selected from the group consisting of clays;silicas; celites; zeolites; metal salts, including for example,phosphates; cellulose, such as methyl cellulose; starches; carbonates,such as sodium bicarbonate; borates, such as sodium borate; sulfatessuch as sodium sulfate; water soluble polymers; borax; and mixturesthereof.
 4. A composition according to claim 3 wherein the meanscontrolling the release of the essential oil from the supportingmaterial is selected from polyethylene glycol, glycerol, mineral oil,and mixtures thereof.
 5. A composition according to claim 1 in the formof capsules wherein the supporting material is a core material and themeans controlling the release of the essential oil from the supportingmaterial is a coating material coating said core material.
 6. Acomposition according to claim 5 wherein the core material is an oilselected from mineral oils, vegetable oils, and animal oils.
 7. Acomposition according to claim 5 wherein the coating material comprisesa protein, carbohydrate or synthetic polymer.
 8. A composition accordingto claim 7 wherein the coating material comprises gelatin.
 9. Use of acomposition as defined in claim 1 to deliver an essential oil havingpesticidal or fungicidal activity to an environment in need oftreatment.
 10. A method of controlling the release of an essential oilhaving pesticidal or fungicidal activity into an environment in need oftreatment comprising the step of applying a composition as defined inclaim 1 onto an area to be treated.
 11. A package containing acomposition as defined in claim 1 said package containing instructionsfor use of the composition as a pesticide or fungicide.